1. Field of the Invention
This invention relates to systems for processing organic material, and more particularly to such systems that reduce emissions of bio-gas and the parasite load on landfills.
2. Description of the Related Art
Recent increases in energy prices has resulted in an increased focus on the use of energy from renewable sources. In particular, the generation of power from bio-gas sources, such as municipal digester and landfills, has become increasingly popular.
A major drawback of utilizing bio-gas from these sources is the contamination of the gas from volatile chemicals that fall into one of three major groups: volatile organic contaminants (such as benzene, toluene and xylene compounds known as ‘BTEX’); volatile inorganic contaminants (such as hydrogen sulfide); and volatile species containing silicon or organosilicons (such as the silanes, silanols, and siloxanes). All three major groups of contaminants are undesirable due to various deleterious properties like corrosivity, toxicity, and physical abrasion to power generation equipment. The organosilicons are the most damaging, often significantly impairing power generation equipment and adding substantial cost to repairs and maintenance. It is readily apparent that it is desirable to remove the corrosive, toxic, and abrasive organosilicons from the bio-gas for more economical operation of power generation equipment.
Heretofore, a semi-fluidized activated carbon bed adsorption system has been used that is regenerated by the semi-fluidization of the spent carbon. Such systems typically use separate vessels for the adsorption and regeneration processes to occur. External pipes and valves are used to transport the spent and regenerated media from one separate chamber to another. This process is most economically applied to power generation systems that use relatively large flows of bio-gas, 1,000 standard cubic feet per minute (SCFM) to 15,000 SCFM.
Unfortunately, the semi-fluidized activated carbon bed absorption systems do not adequately strip or remove contaminates from the carbon media. It is believed that such deficiencies are caused by poor temperature control inside the desorber vessel. Also, bio-gas is able to escape around the valves causing explosive conditions and uncontrolled striping of contaminates from the carbon media. Also, when outside air is used as a transport medium for the carbon media, air contamination of the stripping gas occurs, which can cause explosions.